The game will say a letter in Morse code, it will ask you what letter it was. If you type the correct letter, the screen flashes green, you win. If you type the wrong letter, the screen flashes red and you get another go. If you type "idk" the correct answer will be shown and you will get a new letter. If you type "tex" it will show the letter in text form. If you just hit enter, it will replay the noise.
This quickfire-type game is designed to help you practice and memorise Morse code. I suggest learning a few letters before using this, just so you have a foundation.